Magnetic Energy Storage in the Two Hydromagnetic Types of Solar Prominences

We present analytical solutions that describe the hydromagnetic support of solar prominences in two characteristic configurations, called normal and inverse. We model the corona as axisymmetric outside a unit sphere and treat the prominence as a distributed cold plasma inside a purely azimuthal magnetic flux rope, held in equilibrium by the prominence weight and by an external poloidal magnetic field rigidly anchored to the base of the modeled corona. We focus on the storage of magnetic energy, in particular its potential for driving solar coronal mass ejections (CMEs). Our calculations indicate that both characteristic magnetic configurations are capable of storing enough magnetic energy to overcome the Aly limit for opening up an initially closed magnetic field. These calculations also indicate that magnetic topology is an important influence in magnetic energy storage. Fields with a normal configuration are more likely to attain energetic states leading to CME-type expulsions than those with an inverse configuration, a property we use to explain Leroy's observations of the height distributions of the two types of solar prominences.